The present invention relates to the field of image processing. More specifically, the present invention relates to methods and apparatus for storing a bitstream of digitized video data. Moreover, the present invention is capable of performing such storage using standard dynamic random-access memory (DRAM). This technique is especially suited to digital video applications, where such shuffling is done in order to maintain acceptable image quality. This implementation is suitable for widely-used image compression standards that integrate various algorithms into a compression system, such as the standards specified in the Digital Video Standard (the DV-SD standard, or xe2x80x9cBlue Bookxe2x80x9d), which is included herein by reference in its entirety.
The DV-SD digital video standard outlines the breakdown of a video frame into superblocks and further, into macroblocks (and yet further, into blocks). This is shown in FIGS. 1, 2, 3, and 4. The data is received on a frame-by-frame basis. This data is stored in a frame buffer memory. Compressed video data is transferred in a staggered order, in order to avoid picture degradation. This is done by processing and transmitting the compressed video data in an out-of-order sequence, sending superblock from varied locations in the picture. Thus, if noise is encountered, it appears at several different locations in the picture, rather than clumped together in one area. The former is much more difficult for the human eye to detect, and so picture quality is improved, from a subjective viewpoint.
To simplify the reading and writing of such data, a memory system would normally have enough storage to hold two (or more) frames, and write one while the other was being written. However, due to the size of the video frames and the storage schemes that may be employed, the data for a single video frame requires an odd amount of storage space. One possible solution is to use special purpose memory chips. Such chips would have the proper amount of storage space and addressing to allow whole video frames to be dealt with. Unfortunately, such a solution is expensive. Moreover, such a solution is likely incompatible with other such solutions.
Alternatively, enough standard memory (e.g., DRAM memory) could be used to store two (or more) frames. However, this would result in a large amount of wasted space. While this might be more economical than the use of specialized memories, it would nonetheless cost more than necessary.
What is therefore required is a technique which allows the use of standard memory (e.g., DRAM memory) that uses a minimal amount of-memory while providing the requisite processing throughput.
The present invention solves the problems associated with the prior art by providing methods and apparatus for efficiently and accurately compressing video data.
In one embodiment, a circuit is disclosed for processing audio and video data utilizing conventional DRAMs.